[Removal of Humic Acid from Water Using Pt/biochar Electrode Reactor].

A Pt/biochar electrode reactor was developed to remove humic acid in water. The removal efficiency and characteristics of the reactor were investigated. Experimental results showed that Pt/biochar electrode reactor obtained 74.58% removal rate after 300 min reaction under current density of 20 mA·cm-2. The removal rate was increased by 58.3% comparing with 47.10% removal rate achieved by Pt/graphite electrode reactor. Electrochemical oxidation and air floating played the main roles in removal of humic acid from water. The improved removal efficiency of humic acid in Pt/biochar electrode reactor was attributed to the fact that the biochar cathode could produce more H2O2 than graphite cathode. Three-dimensional excitation emission matrix fluorescence spectroscopy and Gel permeation chromatography measurement revealed that Pt/biochar electrode reactor had strong oxidation capability to mineralize the low molecular weight humic acid directly. It suggests that biochar could be use as an innovative cathode material of electrode reactor for organic pollutants treatment in water.

[Studies of Dynamic Adsorption Behavior of VOCs on Biochar Modified by Ultraviolet Irradiation].

Coconut shell based biochar was modified by ultraviolet irradiation with UV light at a wavelength of 365 nm in order to enhance the adsorption capacity for volatile organic compounds (VOCs). The breakthrough curves of biochars for adsorbing two typical VOCs (benzene and toluene) were examined. The results showed that the adsorption capacity of modified biochar was greatly increased. The saturation adsorption capacity of modified biochar for benzene and toluene was increased to 122.80 mg·g-1 and 236.36 mg·g-1, comparing to that of the pristine biochar (7.27 mg·g-1 and 7.98 mg·g-1, respectively). The breakthrough time of modified biochar for benzene and toluene (390 min and 620 min) was also drastically prolonged as compared to the raw biochar (1 min and 2 min). The characterization analysis of biochars suggested that the carboxylic groups and external surface area were largely enriched, which might be the main factor responsible for the enhanced adsorption of the two VOCs on the modified biochar. The processes of adsorbing benzene and toluene at different concentrations on modified biochar were fitted by Yoon-Nelson, Thomas and BDST models. The result demonstrated that these three models could provide good fitting and the correlation coefficients were all above 0.992. The TG-DTG result proved that ultraviolet irradiation had little effect on the thermal stability of biochar. The modified biochar after adsorption saturation could be reused after thermal regeneration and the regenerated char also had high adsorption capacity after five times of repeated utilization.

Effect of the mixing ratio during co-treatment of landfill leachate and sewage with a combined stripping and reversed A²/O process.

In this study, pilot-scale tests were conducted to evaluate the effect of volumetric mixing ratio of landfill leachate to sewage on the performance of the combined ammonia stripping and reversed anaerobic/anoxic/oxic (A(2)/O) process for co-treatment of landfill leachate and municipal sewage. Stripping, as pre-treatment, could significantly remove ammonia nitrogen (NH3-N) and total nitrogen (TN) by 55% and 52%, respectively. Moreover, chemical oxygen demand (COD) was slightly reduced by 6.8%, and little total phosphorus (TP) was removed. The subsequent reversed A(2)/O process appeared to be highly influenced by the volumetric mixing ratio of leachate to sewage. Typically, the effluent COD, NH3-N, TN and TP increased with the increasing ratio from 1:30 to 1:15, namely, the increasing fraction of leachate. Over the all tested mixing ratio range, the effluent COD and NH3-N were satisfied with the primary B standards of Chinese Discharge Standard of Pollutants for municipal waste water treatment plant (GB18918-2002). The standards different from the primary A standards for water reuse are used for discharge into the most surface water bodies in China. However, TN and TP would exceed the primary B standard levels at a mixing ratio of 1:15 or greater. These findings suggest that an appropriate volumetric mixing ratio should be carefully selected to ensure the performance of the reversed A(2)/O process.

QSPR modeling of n-octanol/air partition coefficients and liquid vapor pressures of polychlorinated dibenzo-p-dioxins.

The molecular geometries of 75 polychlorinated dibenzo-p-dioxins (PCDDs) were optimized using B3LYP/6-31G(*) method. The calculated structural parameters were taken as theoretical descriptors to establish two new novel QSPR models for n-octanol/air partition coefficients (log K(OA)) and subcooled liquid vapor pressure (log P(L)) of PCDDs. The R(2) values of the two models are 0.983 and 0.985 respectively. Their standard deviations of prediction in modeling (SD) are 0.174 and 0.230 respectively. The results of leave-one-out (LOO) cross-validation for training set show that the two models exhibited optimum stability and good predictive power.

[Spectra analysis of dissolved organic matter in pretreatment process of leachate treated by reverse osmosis].

In order to examine the removal of organic matter in the leachate which results in reverse osmosis (RO) membrane fouling, and to provides a reference to select appropriate pretreatment processes of RO, synchronous-scan fluorescence, three-dimensional excitation emission matrix fluorescence spectroscopic and UV-Vis spectrum of the dissolved organic matter (DOM) in different molecular weight range in effluent from each leachate process of "biochemical (UASB+A/O)and UF" pretreatment in some incineration plant were examined. The results of synchronous fluorescence spectra analysis showed that DOM in the wavelength range of 250-320 nm with all the molecular weight and in the wavelength>320 nm with molecular weight>1 KDa was removed obviously by the pretreatment processes. The results of three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectra showed that the pretreatment processes removed low-excitation wavelength tyrosinelike, low-excitation wavelength tryptophan-like and high-excitation wavelength tryptophan-like with all the molecular weight off, and fulvic-like matter and high-excitation wave length tyrosine-like with molecular weight>1 KDa effectively. The results of UV-Vis spectra analysis showed that the pretreatment processes removed DOM of molecular weight>1 KDa with pi-pi transition and DOM of all molecular weight with conjugated system of the benzene ring structure. It was concluded that the removal of both fulvic-like matter and high-excitation wave length tyrosine-like with the wavelength>320 nm, molecular weight<1 KDa and with pi-pi transition should be strengthened for controlling (RO) membrane fouling, when leachate was treated by RO with the pretreatment processes of "biochemical(UASB+A/O)and UF".

[Mechanism of Cr( VI) removal from aqueous solution using biochar promoted by humic acid].

Biochar derived from excess sludge was used for hexavalent chromium [Cr( VI)] removal from water as a sorbent, and impacts of co-existing humic acid on performance of Cr( VI) sorption onto biochar were studied. The experimental results indicated that humic acid facilitated biochar adsorption of Cr(VI), which enhanced capacity of Cr sorption and shortened reaction time reaching equilibrium remarkably. The sorption kinetic process could be described with the pseudo second order model. On the condition of initial pH 4.0, biochar concentration 20 g x L(-1), initial concentration of Cr(VI) in the range of 50-800 mg x L(-1), the Langmuir model fitted adsorption isotherm better than the Freudlich model. The Langmuir Q0 values of biochar with and without existing humic acid were 10.10 mg x g(-1) and 5.56 mg x g(-1), respectively. In the pH range of 2.0-8.0, sorption capacity of all sorbents decreased with increasing initial pH value. Ascending concentration of humic acid in solution promoted sorption capacity of biochar. Fourier transform infrared spectroscopy (FTIR) analysis showed that hydroxyl, carboxyl, ester, aromatic C-H stretch and ring C=C on the biochar were responsible for Cr(VI) sorption. Combined with X-ray photoelectron spectroscopy (XPS) analysis, mechanism of promoting Cr( VI) sorption onto biochar was speculated that humic acid enhanced concentration of Cr( VI) ions aggregating on the surface of biochar and benefited Cr(VI) adsorption coupled with subsequent reduction by biochar functional groups. Meanwhile, humic acid also increased amount of Cr(VI) and Cr(II) removal from aqueous solution.

QSPR models of n-octanol/water partition coefficients and aqueous solubility of halogenated methyl-phenyl ethers by DFT method.

The possible molecular geometries of 134 halogenated methyl-phenyl ethers were optimized at B3LYP/6-31G(*) level with Gaussian 98 program. The calculated structural parameters were taken as theoretical descriptors to establish two new novel QSPR models for predicting aqueous solubility (-lgS(w,l)) and n-octanol/water partition coefficient (lgK(ow)) of halogenated methyl-phenyl ethers. The two models achieved in this work both contain three variables: energy of the lowest unoccupied molecular orbital (E(LUMO)), most positive atomic partial charge in molecule (q(+)), and quadrupole moment (Q(yy) or Q(zz)), of which R values are 0.992 and 0.970 respectively, their standard errors of estimate in modeling (SD) are 0.132 and 0.178, respectively. The results of leave-one-out (LOO) cross-validation for training set and validation with external test sets both show that the models obtained exhibited optimum stability and good predictive power. We suggests that two QSPR models derived here can be used to predict S(w,l) and K(ow) accurately for non-tested halogenated methyl-phenyl ethers congeners.

[Nutrients conservation of N & P and greenhouse gas reduction of N2O emission during swine manure composting].

Nitrogen loss and greenhouse gas (N2O) emission occur during animal manure composting, as well as phosphorus loss caused by runoff during land application of animal manure compost. Therefore, the purposes of this study were to simultaneously conserve nutrients of nitrogen & phosphorus and reduce N2O emission during animal manure composting using modified salts which are made from industrial solid waste. Experiments of in-vessel swine manure composting at lab-scale were carried out to investigate and compare effects of modified red-mud (MR) and modified forsterite (MF) as additives on nutrients conservation and greenhouse gas (N2O) reduction. As far as the nitrogen loss calculated on the basis of ammonia and nitrous oxide is concerned, the least nitrogen loss at only 6.38% of TKN occurred in the swine manure composting with MF addition at pH 7.0 +/- 0.2, compared with those of MR addition at pH 5.0 +/- 0.2 at 11.07% of TKN and the control at 14.68% of TKN, respectively. The best results of ammonia and nitrous oxide mitigation during swine manure composting were the treatments with MR addition and MF addition, which nitrogen losses were at 2.13% of TKN as NH3 and 0.65% of TKN, respectively. These results clearly showed that the modified salt additives from red-mud and forsterite were useful for saving nitrogen and reducing N2O emission. Moreover, the contents of soluble orthophosphate in swine manure compost with the addition of both modified salts were less than that of the control, which is helpful to reduce P loss during land application of swine manure compost.

[Fluorescence of early stage leachates DOM using RO membrane as tertiary treatment].

In the present study, fluorescence spectra of the dissolved organic matter (DOM) extracted from early stage leachate samples obtained from biologically pretreated leachate fed to RO tertiary treatment, the permeated, the concentrate, and liquids collected after cleaning the membrane with acid and then with base were determined. The results of synchronous fluorescence spectra analysis showed the RO membrane effectively removed the high content of organic matter corresponding to short wavelengths of 280, 340, and 370 nm of the feed. Liquids collected after cleaning membrane with acid and base showed obvious influence on the organic pollutant matters in the range of 300-420 nm. The results of three-dimensional excitation-emission matrix (3D-EEM) fluorescence spectra showed three protein-like peaks, namely low-excitation wavelength, tyrosine-like high-excitation wavelength, tyrosine-like high-excitation wavelength, tryptophan-like and two fulvic-like peaks, visible and ultra visible fulvic-like were found in the feed. The permeated contains two peaks with higher intensity than the feed, low-excitation wavelength tyrosine-like and high excitation wavelength tyrosine-like, while the other three peaks were shown in the concentrate. The acid and the base cleaning had great influence on the molecule chemical structure of the organic pollutants on the RO membrane and caused obvious location shifts. It can be concluded that the RO mainly separated the fulvic matter in the early stage leachate and the fouling consisted of fulvic-like matter together with the protein-like, and low-excitation wavelength tyrosine-like.

[Impacts on N and P conservation during swine manure composting with different modified metal-salts addition].

Batch experiments were carried out by using mixed-level uniform design method U6 (692) x 3) to investigate the effect of the addition of different metal-salts at 20%, 40% and 60% of NT, respectively, including modified red-mud (MR) at pH 5.0 +/- 0.2 and 7.0 +/- 0.2, respectively, modified forsterite (MF) at pH 7.0 +/- 0.2, and MgSO4 on nitrogen and phosphorus conservation during swine manure composting. The results showed that the optimum effect of N saved occurred at No. 5 experiment (20%, MF, day 17) and No. 3 experiment (40%, MgSO4, day 10). Meanwhile, the P conservation of experiments with metal salts addition was better than that of the control, and the No. 6 experiment (20%, MR with pH =5, day 21) was the highest on TP conservation, with the lowest ratio of PO4(3-) -P/TP.

Prediction of supercooled liquid vapor pressures and n-octanol/air partition coefficients for polybrominated diphenyl ethers by means of molecular descriptors from DFT method.

The molecular geometries of 209 polybrominated diphenyl ethers (PBDEs) were optimized at the B3LYP/6-31G level with Gaussian 98 program. The calculated structural parameters were taken as theoretical descriptors to establish two novel QSPR models for predicting supercooled liquid vapor pressures (P(L)) and octanol/air partition coefficients (K(OA)) of PBDEs based on the theoretical linear solvation energy relationship (TLSER) model, respectively. The two models achieved in this work both contain three variables: most negative atomic partial charge in molecule (q(-)), dipole moment of the molecules (mu) and mean molecular polarizability (alpha), of which R(2) values are both as high as 0.997, their root-mean-square errors in modeling (RSMEE) are 0.069 and 0.062 respectively. In addition, the F-value of two models are both evidently larger than critical values F(0.05) and the variation inflation factors (VIF) of variables herein are all less than 5.0, suggesting obvious statistic significance of the P(L) and K(OA) predicting models. The results of Leave-One-Out (LOO) cross-validation for training set and validation with external test set both show that the two models obtained exhibited optimum stability and good predictive power. We suggest that the QSPRs derived here can be used to predict accurately P(L) and K(OA) for non-tested PBDE congeners from Mono-BDEs to Hepta-BDEs and from Mono-BDEs to Hexa-BDEs, respectively.

QSPR modeling of n-octanol/water partition coefficients and water solubility of PCDEs by the method of Cl substitution position.

The number of Cl substitution positions (N(PCS)) of all 209 possible molecular structure patterns of polychlorinated diphenyl ethers (PCDEs) were correlated with their partition properties n-octanol/water partition coefficient (lgK(ow)) and sub-cooled liquid water solubilities (-lgS(w,l)). The correlation coefficients (R) and the leave-one-out (LOO) cross-validation correlation coefficients (R(cv)) of all the 6-descriptor models for lgK(ow) and -lgS(w,l) are more than 0.98. By using stepwise multiple regression (SMR), the best two models of lgK(ow) with three descriptors (R=0.9,913) and lgS(w,l) with four descriptors(R=0.9,818) were obtained respectively. Based on these equations, the two properties of all 209 PCDEs were predicted. Model validation showed that the two models exhibit optimum stability and high predictive power. Moreover, results of prediction were further compared with data from similar studies by molecular connectivity indices (MCIs) and PM3 methods.

[Environment load from China's cement production].

Based on the life-cycle theory, a quantitative evaluation of the environment load caused by cement manufacturing in China was carried out with the application of the CML. environmental impact assessment method. The results show that global warming potential, energy depletion potential and abiotic depletion potential make the main contribution to the environment impact, their environmental loads corresponding to identical environmental impact sorts being 2.76%, 2.34% and 1.39% of the overall load of the whole world, respectively. In 2004, the environment load from cement manufacturing in China is roughly 1.28% of the overall load of the whole world, in which the environmental loads from the shaft kiln processing, wet rotary processing and new-type dry processing being 0.84%, 0.12% and 0.32%, respectively. And it can be reduced to about 1% by replacing backward production processes with the dry method production process.